You decide what your cleaning fee covers. Normally this would be for clean linen and towels, the listing being cleaned to a good standard.
Airbnb is not a hotel. I have a shared listing and clean communal areas daily and change bedding/towels and clean rooms weekly.
I think you just need to sit down with guests and explain whatever you cleaning routine covers and that Airbnb is not a hotel service but sharing a home/renting out a whole place (whatever your listing is).
Sounds like they are new to Airbnb so just need some help understanding the concept.
To help future guests might be worth clarifying on your listing.